Implant design modifications partially improved patient outcome following posterior-stabilized TKA: a matched pair
Indelli PF*, Pipino G$, Graceffa A$

*Department of Orthopaedic Surgery and Bioengineering, Stanford University, USA
$ Ludes HEI Malta Campus Lugano

Introduction: Total Knee Arthroplasty (TKA) designs continue to be modified to optimize patient’s outcome. This study showed that patient outcome was only partially influenced by design modifications applied to a classic posterior-stabilized (PS) TKA system.
Methods: A consecutive group of 100 patients undergoing TKA using a classic, second generation, fixed-bearing PS TKA system (PFC Sigma, De Puy, USA) was matched by age, gender, body max index (BMI) to 100 patients having the newer, third generation, fixed-bearing PS design (Attune, De Puy, USA), both by the same manufacturer. Patients were assessed preoperatively, at 12 months and at 24 months minimum follow-up (range, 24-46) in a standard prospective fashion. The outcome assessments used were the Oxford Knee Score(OKS), the Knee Society Score (KSS), range-of-motion (ROM) and a satisfaction survey. A two-sample t-test comparing the two groups was performed.
Results: No patients were lost at follow-up. At 2-year follow-up, differences in clinical and radiological KSS (p=0.09), Oxford Score (p=0.08) and overall satisfaction rate did not reach statistical significance. Implant group 2 (Attune) showed a statistically significant decrease in postoperative anterior knee pain (p=0.006). At final follow-up, 16 % of group 1 knees achieved > 130° flexion compared to 37% in group 2 (p=0.0009). There were two revisions related to patella-femoral complications in group 1 and none in group 2.
Conclusion: This study showed that design modifications applied to a third generation TKA system allowed greater active flexion and a lower rate of anterior-mechanism complications but patients receiving a third generation design did not appear to achieve better overall subjective and objective clinical scores. This study has several limitations, including not being prospective randomized and having a two years minimum follow-up only.

Prof. Gennaro Pipino
Professore Ordinario in Ortopedia
Full Professor Orthopedics Surgery
Direttore del Polo Didattico Unità Clinica e di Ricerca Scientifica in Ortopedia
Facoltà di Scienze Mediche
L.U.de.S HEI Malta Campus Lugan